No problem, but this sounds not that good if you never heard befor of this 
problem.

to your general tips:
- I've saved the logfile here: http://db.tt/19wZdWi
It is rendered with this command and it is all about this one server.
- I will bring this to my boss if we can update the server asap.
- Can the problem be related to the log files?

to the problem itself:
- The Networker version in the client is the following: Version 7.6.1.Build.397
- With this client, the last full backup at 6.8. performed successfully
- Even the backup of small files failed with the same error, there is no 
difference. It also doesn't work on the different directories or different 
drives.
- This server is only a MSSQL DB Server. There is no ather software installed 
(expect Notepad++, 7zip, filezilla, ccleaner and nc_net for nagios, but this 
software is needed).
- What other devices can this be?

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